[R] Frequencies from a matrix - spider from frequencies

Uwe Dippel udippel at uniten.edu.my
Mon Mar 15 16:43:03 CET 2010

Jim Lemon wrote:
> Hi Uwe,
> Here's one way to get your spider plot:
> ld1<-matrix(sample(1:5,310,TRUE),nrow=31)
> ld2<-apply(ld1,2,table)
> radial.plot(ld2,line.col=2:6,rp.type="p",
>   radial.pos=seq(0,9*pi/5,by=pi/5),
>   labels=paste("Q",1:10,sep=""),start=pi/2,
>   clockwise=TRUE,main="Frequency of response by question")
> par(xpd=TRUE)
> legend(8,12,1:5,col=2:6,lty=1)
> par(xpd=FALSE)
> Quite a bit of overlap on the polygons, however.

Thanks, Jim,

this one works (with your random data)! (In case anyone reads and wants 
this as well, package plotrix provides radial.plot.)
The overlap is normal, because it's random data. When the respondents 
have a less random streak of answering (and they do), this plot will 
show some continuity throughout the questions; and identify those 
questions clearly, which fall outside of this continuity.
This is why I prefer to use it here.


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